About 1500 children attending grades K through 12 at five schools in Duplin County, North Carolina, are exposed to fluoridation of the school water supply at four and one-half times the level estimated to be optimum for community fluoridation in the same geographic area. In addition, weekly mouthrinsing with a 0.2 percent NaF solution is done by children in kindergarten through the eighth grade. Teachers dispense 10 millimeters of solution to each participant-child and supervise the one-minute rinsing procedure which is carried out in the classroom. To evaluate the long-term benefits of the combined treatments on the prevalence of dental caries, pre-treatment clinical data will be compared with the data obtained every two years until the completion of the program in 1987. Baseline examinations using the DMF tooth and surface index were conducted in October/November 1975. The project is in its third year. The first follow-up examinations was conducted in September 1977.